+Bob and Rafael > -----Original Message----- > From: Dan Williams <dan.j.willi...@intel.com> > Sent: Friday, April 16, 2021 3:09 PM > To: Andy Shevchenko <andriy.shevche...@linux.intel.com> > Cc: linux-nvdimm <linux-nvd...@lists.01.org>; Linux Kernel Mailing List > <linux-kernel@vger.kernel.org>; Verma, Vishal L > <vishal.l.ve...@intel.com>; Jiang, Dave <dave.ji...@intel.com>; Weiny, Ira > <ira.we...@intel.com>; Kaneda, Erik <erik.kan...@intel.com> > Subject: Re: [PATCH v1 1/1] libnvdimm: Don't use GUID APIs against raw > buffer > > On Fri, Apr 16, 2021 at 1:42 PM Andy Shevchenko > <andriy.shevche...@linux.intel.com> wrote: > > > > On Fri, Apr 16, 2021 at 01:08:06PM -0700, Dan Williams wrote: > > > [ add Erik ] > > > > > > On Fri, Apr 16, 2021 at 10:36 AM Andy Shevchenko > > > <andriy.shevche...@linux.intel.com> wrote: > > > > > > > > On Thu, Apr 15, 2021 at 05:37:54PM +0300, Andy Shevchenko wrote: > > > > > Strictly speaking the comparison between guid_t and raw buffer > > > > > is not correct. Return to plain memcmp() since the data structures > > > > > haven't changed to use uuid_t / guid_t the current state of affairs > > > > > is inconsistent. Either it should be changed altogether or left > > > > > as is. > > > > > > > > Dan, please review this one as well. I think here you may agree with me. > > > > > > You know, this is all a problem because ACPICA is using a raw buffer. > > > > And this is fine. It might be any other representation as well. > > > > > Erik, would it be possible to use the guid_t type in ACPICA? That > > > would allow NFIT to drop some ugly casts. > > > > guid_t is internal kernel type. If we ever decide to deviate from the > > current > > representation it wouldn't be possible in case a 3rd party is using it 1:1 > > (via typedef or so). > Hi Dan,
> I'm thinking something like ACPICA defining that space as a union with > the correct typing just for Linux. I'm assuming that you mean using something like guid_t type for ACPI data table fields like NFIT rather than objects returned by ACPI namespace object such as _DSD. For ACPI data tables, we could to use macros so that different operating systems can provide their own definitions for a guid. For ACPICA, it will expands to a 16-byte array. Linux can have it's own definition that contains a union or their own guid type (guid_t). As long as the OS-supplied definition is 16bytes, I don't think there would be an issue. Bob, do you have any thoughts on this? Erik
